Block synchronization data communication unit in mobile radio

ABSTRACT

A block synchronization data communication unit enables data communication to be properly effected even through a transmission channel under an extremely unfavorable condition as in mobile radio. The block synchronization data communication unit in mobile radio comprises means for encoding data to be transmitted and blocking the encoded data, means for adding a block synchronization signal having a plurality of different successive patterns positioned in a prescribed order to the head of the blocked data, means for transmitting the blocked data added with said block synchronization signal, means for receiving data transmitted, means for recognizing one of patterns constituting the block synchronization signal in the received data, means for estimating the data position based on a block synchronization signal constitution position of the recognized pattern, and means for decoding the blocked data beginning from the estimated position as received data.

RELATED APPLICATION

This application is a divisional application of copending U.S. patentapplication Ser. No. 833,716 filed on Feb. 27, 1986 for "DATACOMMUNICATION SYSTEM WITH BLOCK SYNCHRONIZATION DATA IN MOBILE RADIO"now U.S. Pat. No. 4,694,473.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data communication unit for use inmobile radio such as that in automobiles, and more particularly to acommunication system with use of a block synchronization signal.

2. Description of the Prior Art

A mobile phone system is now commercially available in Japan, Canada,and various countries in Europe, the United State of America, but datacommunication with mobile radio has, at long last, begun to be put intoa practical use. The data communication with mobile radio is mediatedthrough a transmission channel under a severe handicap such as fading.Thus, such data communication may suffer from errors. To solve theproblem, the data in question is commonly subjected to error correctionencoding and is blocked for transmission. A communication system of suchtypes of error correction is called a block synchronization transmissionsystem in which block data signal. Many methods have been proposed up tonow for such systems. An example is described in "Computer-Datacommunication Techniques"--The Elements In Data Communication--, writtenby E. Macnamara, translated by Hiroyuki Watanabe from CQ Publishing Co.,Ltd., PP 138 to 141, wherein two methods are given. One of them a blocksynchronization signal with a single pattern having an arbitrary bitlength and employs it one at a time for transmission. The othertransmits the pattern three times or more in repetition and identifiesit as being a proper block synchronization signal provided that it isreceived two times or more in succession. In addition, another techniqueis given in "Advanced Mobile Phone Service: Control Architecture" by Z.C. Fluhr et al, THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1979, whichdescribes a data format in data communication (P58, FIGS. 8 and 9).However, only with a single pattern, it is not recognized as a blocksynchronization if it is received by mistake. Likewise, with a singlepattern transmitted in a plurality of times, it can be not decided withease from which portion a data fraction begins in the signal if thepattern is received by mistake.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a data communicationunit for effecting block synchronization data communication capable oftransmitting and receiving block data in a proper synchronized relationvia an extremely bad-conditioned transmission channel as in mobile radiosuch as that in automobiles.

A block synchronization data communication unit in mobile radioaccording to the present invention comprises:

(1) means for encoding data to be transmitted and blocking the encodeddata,

(2) means for adding a block synchronization signal having a pluralityof different successive patterns positioned in a prescribed order to thehead of the blocked data,

(3) means for transmitting the blocked data added with the blocksynchronization signal,

(4) means for receiving data transmitted,

(5) means for recognizing one of patterns constituting the blocksynchronization signal in the received data,

(6) means for entimating the data position based on a blocksynchronization signal constitution position of the recognized pattern,and

(7) means for decoding the blocked data beginning from the estimatedposition as received data.

The above and other objects, features and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings in which a preferredembodiment of the present invention is shown by way of illustrativeexample.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematical view illustrating a data communication system inmobile radio,

FIG. 2 is a view illustrating a prior block synchronization system,

FIGS. 3a-3d are views illustrating a block synchronization systemaccording to the present invention,

FIGS. 4a1-4a3 represent a circuit block diagram of a data modem on theland side with use of the block synchronization system according to thepresent invention, and

FIGS. 4b1-4b3 represent a circuit block diagram of a mobile cellularmodem with use of the system according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, illustrating a data communication system in mobile radio,designated at 1 is a computer, 2 is a telephone set, 3 is a land modem,4 is a public switching telephone network 5 is a mobiletelecommunications switching office (MTSO), 6 is a cell site, 7 is amobile, 8 is a mobile telephone transmitter/receiver unit (TRU), 9 is acellular modem, 10 is a control unit (CU), and 11 is a computer. Theabove members from the computer 1 to the cell site 6 are located on theland side, while those from the TRU8 to the computer 11 are carried onthe mobile 7.

Referring to FIG. 1, data communication between the computer 1 on theland side and the computer 11 carried on the mobile 7 will be described.Although the computer 1 and the telephone set 2 are connected with theland modem 3, the computer 1 is connected with the land modem 3 byswitching the system to a data mode. Data from the computer 1 issupplied in a block unit to the land modem 3 in which it is subjected toerror correction encoding, and then fed to the public switchingtelephone network 4. The data is further allowed to pass, via the MTSO 5and the cell site 6, through a radio communication interval, andreceived by the mobile phone transmitter/receiver unit (TRU)8 of themobile 7. The received data is subjected to decoding, etc., by thecellular modem 9 which then delivers the data to the computer 11 as thedata is decided to be normal. Provided that the received data is decidedto be an erroneous one, the mobile side requests the land side toretransmit the same block data. Effecting the above procedure inrepetition block data is transferred from the computer 1 on the landside to the cellular modem 9 of the mobile 7. The same procedure iseffected also when, in contrast with the situation, data is transmittedfrom the computer 11 of the mobile 7 to the computer 1 on the land side.Moreover, communication can also be achieved by phone between thetelephone set 2 and the control unit (hand set) 10 of the mobile 7.

It is general in a data communication system in mobile radio to employ ablock synchronization signal to transfer block data.

Prior to describing the block synchronization communication systemaccording to the present invention, a conventional method such, forexample, as those described in the literature mentioned before, etc.,will be described with reference to FIG. 2. As shown in FIG. 2 showingfading experienced by a signal in mobile radio, a signal higher than areception limit level can be received without any error, whereas thatlower than the level can be received by mistake. In case of FIG. 2(B)illustrating an example wherein a block synchronizing signal comprises asignal pattern, a hatched portion of the signal is not properlyrecognized as a block synchronization signal since that portion iserroneously received. On the other hand, another block synchronizationcommunication system is shown in FIG. 2(C) wherein the same pattern intransmitted three times in repetition, and the data is recognized as aproper block synchronization signal provided that two succeedingpatterns can be found. Namely, although the first of the patterns is notproperly recognized as a synchronization signal because of its erroneousreception, the second and third patterns are recognized as a blocksynchronization signal because of their proper reception. However, whena block synchronization signal only comprises a single pattern as shownin FIG. 2(B), the signal is not recognized as a block synchronizationsignal provided that it is received by mistake, while in case of FIG.2(C) it is difficult to decide at what position a sequence of theproperly recognized block synchronization signal is located among thethree block synchronization signals.

Against this, with the block synchronization system according to thepresent invention, a plurality of different subsequent patternsconstruct a block synchronization signal, and a pattern constituting theblock synchronization signal is recognized on the receiving side, and adata position is estimated based on the properly recognized patternposition for block synchronization.

In FIG. 3 illustrating a block synchronization communication systemaccording to the present invention, solid and dotted curved lines ofFIG. 3(A) respectively shown signal fading and a straight line on thehorizontal axis represents a reception limit level. A blocksynchronization signal for use in the present embodiment is shown inFIG. 3(B), which comprises three kinds of successive patterns of SYNC1,SYNC2, and SYNC3 each being composed of 15 bits. SYNC1, for example,employs "111101011001000", SYNC2 "000010100110111" and SYNC3"000100110101111". The receiving side supervises the three kinds of thepatterns of SYNC1, SYNC2, and SYNC3. The receiving side recognizes anypattern thereamong for detecting the position of the pattern in theblock synchronization signal, and estimates the first position of thedata in question.

Let us, for example, consider here a case wherein a blocksynchronization signal shown in FIG. 3(B) is received as shown in FIG.3(C) under a fading pattern shown by a solid line FIG. 3(A). It isassumed that the pattern of SYNC1 including a portion less than thereception limit level is erroneously received while the other patternsof SYNC2 and SYNC3 are received properly. In the instance, the data inquestion is decided to begin on and after 16th bit (from the position ofX on) since the pattern of SYNC2 previously properly recognized could beproperly recognized (There is no problem even if SYNC3 is erroneous).

Then, let us consider a case wherein the block synchronization signalshown in FIG. 3(B) is received as shown in FIG. 3(D) under a fadingpattern shown by dotted line in FIG. 3(A). The patterns of SYNC2 andSYNC3 including a portion less than the reception limit level areerroneously received while the pattern of SYNC1 is properly received.Accordingly, in this case, the data in question is decided to begin onand after the 31th bit (from the position of Y on) since SYNC1 wasrecognized.

The block synchronization transmission system according to the presentinvention is employed in both devices of the data modem 3 on the landside and the cellulor modem 9 of the mobile 7, as shown in FIG. 1.Circuit block diagrams of the land modem 3 and the cellular modem 9 arerespectively shown in FIGS. 4a and 4b, wherein designated at 301 is aprocessor, 310 is a RS-232C interface, 313 is a power supply and 317 amodem. A computer 1 is connected with a RS-232C interface port 342, atelephone set 2 connected with a TELSET interface 340, and a publicswitching telephone network 4 connected with a TELCO interface 341, asshown in the same figure.

Operation of data transmission from the land modem 3 on the land side tothe mobile 7 will be described below.

First, a switch 324 is operated whereby whether the mode in question istransmission one or a reception one is detected in an ORG/ANS LogicFunc. part 325. The present case is set to transmission. Thetransmission mode is supplied to a CPU302 of the processor 301 via aperipheral interface 322, whereby the CPU302 is informed of a start ofthe transmission. Then, the CPU302 interrogates the RS-232C interface310 about whether the computer 1 connected the RS-232C interface 310 isready or not. Then, data to be delivered from the computer 1 isincorporated in a RAM304 via the processor part 301 and the RS-232Cinterface 310, and subjected to error correction encoding for preparingblock data. In case of data communication through the telephone, sincethe land modem 3 is connected to the telephone 2 via the TELSETinterface 340, a line switch 329 is, upon initiating the datacommunication, switched to the TELCO interface 341 whereby the landmodem 3 is connected with the public switching telephone network 4. TheCPU302 waits an ACK signal (reception-ready signal) from the mobile 7 onthe receiving side. The ACK signal is entered in the land modem 3 viathe TELCO interface 341, demodulated by a modem part 317, andincorporated in the processor 301 via the peripheral interface 319. Themodem 317 is a well known type and so operation thereof will not bedescribed here. The CPU 302, upon receiving the ACK signal, starts totransmit the blocked data which has already been stored on the RAM 304.Furthermore, the CPU302, upon transmitting each block data, adds a blocksynchronization signal to the head thereof. The block synchronizationsignal comprises three kinds of patterns of SYNC1, SYNC2, and SYNC3 eachpattern being composed of 15 bits, as shown in FIG. 3(B). The block dataadded with the block synchronization signal is delivered to the publicswitching telephone network 4 via the RAM 304, a peripheral interface319, a modern 318, the line switch 329, and the TELCO interface 341, andtransmitted to the mobile 7 via the MTSO5 and the cell site 6.Successive data from the computer 1 are likewise subjected to errorcorrection encoding and added with a block synchronization signal in theRAM 304 for transmission.

Operation of the mobile 7 which receives the transmitted data will bedescribed with reference to FIGS. 1 and 4b. The transmitted data isreceived by the mobile phone transmitted receiver unit 8 of the mobile 7and transferred to the cellular modem 9. As shown in FIG. 4b, designatedat 901 is a processor part, 910 is a RS-232C interface, 913 is a powersupply and 917 is a modem. The computer 11 of FIG. 1 is connected with aRS-232C interface port 942, and the mobile phone transmitted receiverunit (TRU) 8 and the control unit (CU) 10 are connected with a TRU/CUinterface port 940. The data received by the mobile phonetransmitter/receiver unit (TRU) 8 is supplied to the modem 917 via theTRU/CU interface port and an audio path switch 932. The modem 917demodulates the received modulated data and delivers it to the RAM 904of the processor 901 via a peripheral interface 919. Here, the audiopath switch 932 serves to switch a path for an audio signal between thedata mode and the conversational mode. The CPU 902 decodes the data sentto the RAM 904. In succession, for the received data, it is checkedwhether the data is a block synchronization signal or not. It isinvestigated at what position any of same patterns as those three kindsof the block synchronization signal (SYNC patterns) each patterncomprising 15 bits shown in FIG. 3(B) are in the received data. Theprocessor 901 decides, as described in FIG. 3(C), based on the patternof SYNC 2 as properly recognized, that the data in question begins onand after the 16th bit (shown by x) from that pattern, while theprocessor 901, if it properly recognizes the pattern of SYNC 1 as shownin FIG. 3(D), decides that the data begins on and after the 31th bitfrom that pattern (shown by Y in the FIGURE). The received data isdecoded and is, if properly received, delivered to the computer II viathe RS-232C interface 910 and the RS-232C interface port 942. Likewise,data transmitted from the computer 1 on the land side are transmitted insuccession to the computer II on the mobile. Also in a case where anydata is transmitted from the computer II on the mobile side to thecomputer 1 on the land side, the same procedure as described above canbe effected.

Although in the above embodiments, the block synchronization signal iscomposed of the three kinds of successive patterns of SYNC 1, SYNC 2,and SYNC3, a block synchronization signal composed of two kinds ofpatterns or three kinds or more of patterns will be likewise applied.

According to the present invention, as described above, since a blocksynchronization signal is constituted by a plurality of patterns,provided that only one thereamong can be recognized, the blocksynchronization signal can be recognized even if the remaining patternsare erroneous. In addition, it can be advantageously decided from thatposition the data in question begins.

The present invention can profitably employed for all data communicationwhere fading in a mobile phone, etc., is troubled.

Although a certain preferred embodiment has been shown and described, itshould be understood that many changes and modifications may be madetherein without departing from the scope of the appended claims.

What is claimed is:
 1. A block synchronization data communication unit in a mobile radio comprising:(1) a transmitting part including:(a) a means for encoding data and forming said data into blocks to be transmitted; (b) a means for adding a block synchronization signal, having a plurality of different successive patterns positioned in a prescribed order, to said data formed into blocks; (c) a circuit means for modulating said data formed into blocks with said block synchronization signal, and (2) a receiving part including:(a) a receiver means for receiving data; (b) a circuit means for demodulating said received data; (c) a means for decoding said demodulated received data; and (d) a means for recognizing one of said patterns constituting said block synchronization signal and for estimating the data position based on a position of said recognized pattern in said plurality of different successive patterns. 